Magnetic read heads are used in hard disk drives to sense magnetic signals from disks spinning beneath the read heads and, thus, to read data on the disks. To control the stability and magnetic moment orientation of the sensor layer of the head, a bias field can be provided by hard bias magnet layers that are disposed next to the sensor layer at its two side edges.
As recognized by the present invention, a mismatch can occur between the physical read width of a read sensor and its magnetic read width. Generally, for longitudinal recording, the magnetic read width is larger than the physical read width, meaning that to achieve small magnetic read widths to facilitate denser data storage, the physical dimension of the read head must be made even smaller. This complicates manufacturing of the read head.
A contributing factor to the above-noted mismatch problem is that the electrical lead connecting the read head to external circuitry can have varying degrees of thickness from the center of the sensor to the track edge. One way to address this problem is to make the leads very thin, so that the top surface of the sensor and the top surface of the lead are substantially coplanar. But the present invention understands that such a thin lead produces unacceptably high resistance.
The present invention further understands that to alleviate the high resistance problem posed by a single very thin lead, an upper lead layer can be deposited on the thin lead. However, this in turn creates its own problem, namely, that the upper lead layer requires critical alignment that can exceed the capacity of the fabrication tooling, and in particular the overlay capacity of steppers. Poor overlay can result in sensor shorting. Moreover, the process can be jeopardized by poor resist undercut control, leading to so-called “fences” that might cause shorts, ESD sensitivity, and gap flare and, thus, detract from read head performance.
Having recognized the above problems, the solution herein is provided.